Post-event modification of local clock values in water distribution system

Abstract

A hydrant apparatus may be employed to monitor a water distribution system, and may include a sensor, a processor, and a local clock source. The apparatus may wake from a low power mode to a sensing mode, receive the sensor data, associate the sensor data with a first local clock time, and return the apparatus to the low power mode from the sensing mode. The apparatus may subsequently wake to an operational mode, determine a second local clock time subsequent to the first local clock time, associate an external clock time with the second local clock time, determine an offset for the received sensor data based on the first local clock time and the association between the second local clock time and the external clock time, and transmit the sensor data and the offset to an external monitoring system.

What is claimed is: 
     
       1. A remote monitoring system for a water distribution system, the remote monitoring system comprising:
 a plurality of hydrant apparatuses, each apparatus corresponding to a hydrant of the water distribution system, the hydrant apparatuses each including:
 a sensor configured to output sensor data relating to at least one operating parameter of the water distribution system; 
 a processor in communication with the sensor; 
 a local clock source; 
 a communication interface; and 
 a memory, wherein the memory includes instructions that when executed by the processor cause the apparatus to:
 receive the sensor data from the sensor; 
 associate the sensor data with a first local clock time determined by the local clock source; 
 obtain an external clock time from an external clock source; and 
 determine an offset for the received sensor data based on a difference between the local clock time and the external clock time; and 
 
 
 a central monitoring system in communication with each of the plurality of hydrant apparatuses via the respective communication interfaces of the plurality of hydrant apparatuses, wherein the central monitoring system is configured to, in response to a detected water system event, receive the respective sensor data, the respective local clock time associated with the sensor data and the respective offset from each of the plurality of hydrant apparatuses. 
 
     
     
       2. The remote monitoring system of  claim 1 , wherein the central monitoring system is further configured to determine normalized times for the sensor data from each of the hydrant apparatuses based on the respective offsets. 
     
     
       3. The remote monitoring system of  claim 2 , wherein the central monitoring system is further configured to identify a location of the water system event with respect to the plurality of hydrant apparatuses based on the normalized times for the sensor data from each of the hydrant apparatuses. 
     
     
       4. The remote monitoring system of  claim 3 , wherein the central monitoring system is further configured to identify the location based on one or more known locations associated with the plurality of hydrant apparatuses. 
     
     
       5. The remote monitoring system of  claim 2 , wherein the central monitoring system is further configured to measure a speed of the water system event based on the normalized times for the sensor data from each of the hydrant apparatuses. 
     
     
       6. The remote monitoring system of  claim 2 , wherein the central monitoring system is further configured to measure a change of a rate of propagation of the water system event based on the normalized times for the sensor data from each of the hydrant apparatuses. 
     
     
       7. The remote monitoring system of  claim 2 , wherein the central monitoring system is further configured to measure a rate of dissipation of the water system event based on the normalized times for the sensor data from each of the hydrant apparatuses. 
     
     
       8. The remote monitoring system of  claim 2 , wherein the central monitoring system is further configured to determine a cause of the water system event based on the normalized times for the sensor data from each of the hydrant apparatuses. 
     
     
       9. The remote monitoring system of  claim 8 , wherein the determination of the cause of the water system event comprises distinguishing between a plurality of potential causes based on the normalized times for the sensor data from each of the hydrant apparatuses. 
     
     
       10. The remote monitoring system of  claim 9 , wherein the determined cause of the potential causes comprises a usage spike, a pressure hammer, an accident, a leak, water theft, or pipe blockage. 
     
     
       11. The remote monitoring system of  claim 2 , wherein the central monitoring system is further configured to automatically compensate for the water system event based on the normalized times for the sensor data from each of the hydrant apparatuses. 
     
     
       12. The remote monitoring system of  claim 11 , wherein the automated compensation comprises changing a water pressure provided to a location associated with the water system event. 
     
     
       13. The remote monitoring system of  claim 12 , wherein the changing the water pressure comprises sending a signal to modify the operation of a valve or a booster pump of the water distribution system. 
     
     
       14. The remote monitoring system of  claim 2 , wherein the central monitoring system is further configured to provide a suggested action to a service operator based on the normalized times for the sensor data from each of the hydrant apparatuses. 
     
     
       15. The remote monitoring system of  claim 1 , wherein the memory further includes instructions that when executed by the processor cause each apparatus to determine a respective drift associated with the local clock source, wherein the offset of the hydrant apparatus associated with the local clock source is determined based on the respective drift. 
     
     
       16. The remote monitoring system of  claim 1 , wherein the sensor comprises a pressure sensor and the at least one operating parameter comprises pressure. 
     
     
       17. A method of monitoring a water distribution system via a plurality of hydrant apparatuses, the method comprising:
 receiving, at each hydrant apparatus of the plurality of hydrant apparatuses, respective sensor data relating to at least one operating parameter of the water distribution system, each hydrant apparatus corresponding to a hydrant of the water distribution system, each hydrant apparatus of the plurality of hydrant apparatuses including a sensor configured to output the sensor data, a processor in communication with the sensor, a local clock source, and a communication interface; 
 associating, by each hydrant apparatus of the plurality of hydrant apparatuses, the respective sensor data with a first local clock time determined by the respective local clock source; 
 obtaining, by each hydrant apparatus of the plurality of hydrant apparatuses, an external clock time from an external clock source; 
 determining, by each hydrant apparatus of the plurality of hydrant apparatuses, a respective offset for the received sensor data based on a difference between the local clock time and the external clock time; 
 detecting, by a central monitoring system, a water system event; 
 transmitting, by each hydrant apparatus of the plurality of hydrant apparatuses, the respective sensor data, the respective local clock time and the respective offset to the central monitoring system in response to the detected water system event; 
 and 
 determining, by the central monitoring system, normalized times for the sensor data from each of the hydrant apparatuses based on the respective offsets for the respective sensor data. 
 
     
     
       18. The method of  claim 17 , further comprising identifying a location of the water system event with respect to the plurality of hydrant apparatuses based on the normalized times for the sensor data from each of the hydrant apparatuses. 
     
     
       19. The method of  claim 17 , further comprising measuring a change of a rate of propagation of the water system event based on the normalized times for the sensor data from each of the hydrant apparatuses. 
     
     
       20. The method of  claim 17 , further comprising determining a cause of the water system event based on the normalized times for the sensor data from each of the hydrant apparatuses, wherein determining the cause of the water system event comprises distinguishing between a plurality of potential causes based on the normalized times for the sensor data from each of the hydrant apparatuses.